During road construction, storm drains (also known as catch basins) and sewer inlets are disposed at various points along the road to evacuate excess water and/or debris that may accumulate. Such accumulation can occur for example during rainfall.
The storm drains (or catch basins) are connected to a system which is a network of pipes, pumps, and force mains for the collection of wastewater, or sewage, from the community. Typically, storm drains use a separate and distinct network from sanitary sewer systems for human waste. Sometimes a combined system provides only one network for all types of sewage and excess water or debris.
In order to evacuate the excess water and debris toward the system, the storm drain includes an inlet disposed on the road surface. Two main types of inlets exist: the side inlet and the grated inlet. The typically ends in an outlet for the water which is a single large exit at the point of discharge. The separation of storm sewers from sanitary sewers helps to prevent sewage treatment plants becoming overwhelmed by infiltration/inflow during a rainstorm, which can result in untreated sewage being discharged into the environment.
The grated inlets prevent pedestrians, vehicles and large objects from falling into the storm drain. The design of the grate bars facilitates a flow of water towards the inside of the drain. Storm drains provided in streets and parking areas must be strong enough to support the weight of the vehicles. The grate is usually relatively small to avoid reducing the structural integrity of the road on which vehicles travel. Some of the heavier sediment and small objects or debris may enter the grated inlet and settle in the catch basin below the inlet. A frame is provided for the catch basin or catch pit and the grate covers the open top of the frame of the catch basin. The frame supports the grate/cover.
To optimize the flow of water, the grate is often positioned close to the curb and the surface of the road is slightly angled away from the middle of the road to allow water to flow towards the grate and into the catch basin.
Some frames include a lower flange which is adapted to rest on top of the inlet of the catch basin, such that the vertical passageway may be positioned adjacent to the curb with part of the passageway being vertically above the inlet and part of the passageway being vertically above a portion of the rim of the inlet.
Unfortunately, this configuration creates an elbow which reduces the water flow efficiency of the catch basin. Furthermore, the lower flange may not fit adequately on the rim of the inlet and a portion of the flange may overhang above the inlet of the catch basin instead of being fully supported by the rim of the inlet. This configuration may therefore not be adapted to properly support the loads created by vehicles travelling near the curb.